Frameless Stereotaxy in Stereoelectroencephalography Using Intraoperative Computed Tomography

Area of Science:

• Neurosurgery
• Epileptology
• Medical Imaging

Background:

• Pharmacoresistant epilepsy impacts ~33% of patients, necessitating advanced diagnostic and surgical interventions.
• Focal epilepsy surgery offers improved outcomes for selected patients, requiring precise localization of the epileptogenic zone (EZ).
• Stereoelectroencephalography (SEEG) is crucial for EZ localization, especially in MRI-negative or inconclusive cases.

Purpose of the Study:

• To evaluate the safety, feasibility, and accuracy of frameless stereotactic SEEG electrode implantation using automated CT-based registration.
• To assess the precision of this technique by measuring electrode placement accuracy.
• To compare the accuracy of frameless SEEG with established frame-based methods.

Main Methods:

• Retrospective analysis of 22 pharmacoresistant epilepsy patients undergoing frameless stereotactic SEEG.
• Automated CT-based registration for intraoperative electrode placement guidance.
• Calculation of Euclidean, radial, angular, and depth deviations for 153 implanted electrodes.

Main Results:

• Median Euclidean distance at entry: 1.54 mm; at target: 2.61 mm.
• Median radial deviation at entry: 1.33 mm; at target: 1.67 mm.
• Accuracy was not significantly influenced by electrode order, location, skull thickness, or length.

Conclusions:

• Frameless stereotactic SEEG with automated CT registration is a safe, feasible, and precise method for EZ identification.
• This technique offers accuracy comparable to frame-based SEEG while maintaining workflow efficiency.
• Larger cohort studies are recommended to confirm findings and evaluate surgical outcome impact.